Grenco Science G Pen Pro Review

The G Pen Pro from Grenco Science is a portable dry herb vaporizer boasting a compact design, three temperature settings and an impressive $90 price-tag, but does it perform well enough? We test the device out in our G Pen Pro review.

G Pen Pro Dry Herb Review
Bottom Line
The G Pen Pro is the ideal middle-ground for dry herb vaporizers from Grenco Science’s selection, and the performance is great considering its compact size. Heavy users might prefer the expanded battery life of the Elite, but for occasional vapers the Pro is ideal.
Build Quality
User Review0 Votes
Three temperature settings from 375 °F / 190 °C to 428 °F / 220 °C
Single-button operation – really easy to use
Ceramic chamber
Solid performance at all temperatures
LED indicator lights
Excellent price of $89.99
Quick heat up
Compact and lightweight
Stylish design
Shorter battery life than many options, but still good
Other devices have more temperature options
The flavor drops off notably towards the end of your session
The chamber is a little small, especially for regular users
G Pen Pro

Is it worth picking up?

The G Pen Pro strikes a great balance between the slightly too small Nova and the chunkier, more expensive Elite, and it’s a fantastic option for a newer vaper on a budget.

It performs well, and although heavier vapers may prefer the expanded battery life of the Elite, the Pro does more than enough if you vape every so often and don’t want to spend too much on a solid setup. It’s portable, affordable, easy to use, well-designed and dependable.

For $89.99, it’s a great deal, and while it’s worth considering something more feature-packed if your budget it higher, it’s a solid contender in its price-range.

Full review

Grenco Science G Pen Pro Dry Herb

Grenco Science’s G Pen series covers a lot of ground. As well as spanning three sizes – from the thinner Nova to the chunky Elite – there are also options for dry herb in addition to concentrates, and the new Gio offering support for marijuana e-juice pods in some states. So whether you’re looking for something that suits you for an occasional vape or daily companion, there will be a G Pen to suit you. The G Pen Pro is the mid-size option, a bit thicker than an average vape pen and costing just under $90. It only supports dry herb, but for the price and the portability it’s definitely a tempting-looking device. But does the reality live up to the expectations? Our G Pen Pro review puts it to the test to find out.

What You Get

G Pen Pro Unboxing

The G Pen Pro comes in a unique cylindrical container, all black with simple branding, an outline sketch of the vaporizer and a list of contents around the outsides. The top pulls off, and inside your device sits in a cylinder of foam. The other half contains the USB charging cable, the G Pen Tool and a mini pipe-cleaner like cleaning brush. The cylinder opens up to reveal a simple instruction manual for the G Pen Pro, a pretty cool design overall. The tool is a nice addition, but it is a fairly standard selection for a cannabis vaporizer.

Grenco Science G Pen Pro Review – The Design

G Pen Pro Vaporizer Design


The G Pen Pro is a jet black, roughly-cylindrical vaporizer pen that’s about the thickness of your thumb and the length of a standard vape pen. The cross-section is like a rounded triangle towards the top, but more circular towards the bottom. Grenco Science has kept everything simple, with nothing on the body of the device aside from a button with a leaf symbol, four spots for the small LEDs and a “G” logo light underneath. All of this is on the front face, which is slightly set apart from the rest of the device by two long, shallow trenches cut into the body around it. The bottom of the vaporizer has the USB charging port flush to the surface, and the mouthpiece slopes upwards towards the back, with a small hole in the upper end for airflow.

Overall the Pro looks really cool; they’ve kept it simple while maintaining a certain elegance. They clearly took care over the design.

The Chamber

G Pen Pro - Ceramic Chamber

You add your dry herb to the chamber at the top of the Pro, which you access by simply pulling off the mouthpiece. The chamber itself is quite thin and longer than you’d expect, and it holds 0.25 g of material, which is pretty impressive for such a compact device – definitely enough for a session. The whole chamber is ceramic, which is ideal for heat resistance and it also won’t impart any flavor during vaping. It’s a conduction heating device, which isn’t a surprise considering the low price, but this works well enough for most users and is well worth making it more affordable. Overall it’s really well-designed, I’d prefer a slightly thicker and shallower chamber, but what they’ve done is executed perfectly.

The Mouthpiece

G Pen Pro Review - Mouthpiece

The mouthpiece on the Pro has a silicone covering, which makes it pretty comfortable to hold between your lips in combination with the sloped tip. The hole for airflow is quite small, but sits just in the right place for you to inhale when using the device. On the underside of the mouthpiece there’s a filter – a metal disc with an array of small holes – to catch any debris and make sure you only pull up vapor when you puff. It pops on and off of the device easily, and you can also remove the silicone cover from the mouthpiece to reveal the plastic body for easy cleaning. The silicone cover wraps around the underside of the mouthpiece slightly to make sure it stays in place.

The Button

G Pen Pro Display

The button on the G Pen Pro is located about half way up the body of the device, just sticking out from the surface slightly with a line-drawing of a leaf on the front. The circular button pushes in really easily and gives a satisfying click when you press it down. It’s well-positioned for comfortable use, placed just about where your thumb or index finger naturally falls when you pick it up.

LED Lights

G Pen Pro - Temperature Setting LEDs

Underneath the fire button, there’s a series of four small LED light and the “G” icon light. These are there to indicate your settings and let you know when the device is heating, charging or ready to vape. The lights are multi-color, so they light up blue to show the lowest setting, green for the middle setting and red for the highest setting. When the device is heating up (after you press the fire button five times in quick succession), the four LED lights pulse gradually (in the color appropriate for your setting) and the “G” illuminates. When it’s reached vaping temperature, they light up solid. Finally, during charging the lights fill up sequentially (in white) until charging is complete, when they stay lit solidly. This is a really effective way to convey a lot of information without a screen.

G Pen Tool

The G Pen Tool included with the device is designed to help you tap your material down into the chamber and scoop the ABV (already been vaped) out when you’re done. The tool is attached to a keyring loop – although I can’t imagine you’d need to keep with your keys unless you were very serious about vaping – and is pretty simple in design. It’s thicker at the keyring-end, with a square profile and flattened sides so it’s easy to hold, and then thins out into a wedge-shape at the other side. The thicker, flat side is really useful for tapping your material down into the chamber too.


The design of the G Pen Pro is pretty straightforward, but it’s elegant in its simplicity, getting everything done without unnecessary clutter or complications. It does everything you need it to, but manages to stay about as simple as you could expect from any vaporizer pen.

Grenco Science G Pen Pro Review – Features and Performance

Grenco Science G Pen Pro Features

Temperature Settings

There is really only one feature on the G Pen Pro: the ability to choose between three temperature settings. These settings are:

  • Blue: 375 °F / 190 °C
  • Green: 400 °F / 204 °C
  • Red: 428 °F / 220 °C

This covers more than enough ground for most vapers. While only having three options doesn’t offer you quite as flexibility as a free choice of temperature or some other devices that give you more options, in practice you’ll be able to have a great vaping experience with these settings. They’re separated by about 25 °F each, so they manage to cover a pretty large range while still giving you choices for the sort of experience you’ll have.


The G Pen Pro performs quite well overall. Despite it being a pretty compact vaporizer, the Pro vaporizers your herbs evenly and efficiently, and puts out visible – though not huge – puffs of vapor after an average-length draw. The chamber is ceramic, so there is no impact on your flavor from this at all, although a glass mouthpiece would have improved the taste. The flavor is vibrant and pure at the start of your session, but it does drop off notably towards the end where there is more of a noticeable plastic-y tinge to the vapor.

The 0.25 g chamber size gives you enough room for a session’s worth of material, but depending on your tolerance you might need a little more to get to good level. The airflow is pretty tight, but this is perfect for a dry herb vaporizer because it’s a much slower process than concentrate or e-liquid vaping.

The Pro reaches vaping temperature in less than 30 seconds, even on the highest setting. This is great and it heats up much more quickly than you’d expect, and produces plenty of vapor from the moment the lights activate solidly. The session length is four minutes, which I never find to be quite enough but the impressive efficiency of the G Pen Pro means that you’re unlikely to need too much longer to vaporize the whole chamber’s worth of bud.

Overall it works excellently – performing as well as high-end devices many times the price. No complaints at all.

Battery Life and Recharging

Grenco Science G Pen - Battery Life Indicator

The G Pen Pro’s small size means that battery life is always going to be something of an issue. The battery life depends largely on the setting you’re vaping at, but you can expect between 30 minutes and an hour of continuous use out of the device. This might not sound like a lot, but converted into sessions that means you can get between 7 and 15 four-minute blocks out of the device before it needs recharging. The LEDs on the front of the device decrease throughout the charge, from all four down to one, and flash five times when it needs to be recharged.

To recharge, you simply connect the included micro USB cable to the bottom of the device and plug into a laptop. It charges within three hours, which is about average for cannabis vaporizers. The LED lights remain solidly-lit when it’s fully-charged.

Grenco Science G Pen Pro Review – In Use

G Pen Pro - In Use

Ease of Use – Switching on and Changing Settings

If you’re new to cannabis vaping, you might be wondering whether the G Pen Pro is difficult to get used to using. The good news is that this is about as easy as it can be, with the single-button operation of the device cutting any unnecessary complications out of the most basic tasks. Switching the device on just takes five quick presses of the button, and when it’s heating, you press and hold the button for three seconds to cycle through the next temperature setting. You can deactivate the device with another five presses, and that’s all you’ll need to do.

Ease of Use – Filling, Emptying and Cleaning

When it comes to loading up the chamber, the G Pen Pro also makes it about as simple as can be. All you have to do is pop off the mouthpiece – just give it a little wiggle and pull upwards – and then load your material into the space. The ceramic portion is easy to see so you won’t overfill, so actually getting your bud into the opening is the most difficult part of filling up. The G Pen Tool is really helpful for this, though, and it makes emptying the ABV really easy too.

Cleaning the Pro is pretty easy too: wait for it to cool down after emptying, then brush any debris out of the chamber with the included cleaning brush. The mouthpiece can be soaked in isopropyl alcohol to remove any residue clinging to the filter from continued use, and then you simply rinse it with warm water and allow it to dry. You can pick up replacement mouthpieces for $4.95 too, and I'd recommend picking up a couple of extra ones if you're buying the vaporizer, because it does start to pick up residue quite quickly and cleaning can only take you so far.

 Comfort and Portability

The G Pen Pro strikes a really nice balance between being big enough to pack a punch and vaporize your herb properly but still small enough to carry with you out of the house. It’s not substantially bigger than even a basic vape pen, and it’s smaller than many vaporizers that perform at its level. The rounded triangular shape also makes it really comfortable to hold and use: it fits beautifully in your hand and vaping with it feels natural and comfortable. Everything has been designed to be user-friendly and they’ve done a great job overall.

 Build Quality

Grenco Science G Pen - Manufacturing Quality

The G Pen Pro is really well put together. The device itself has a solid feel and an aluminum body, making it both lightweight and durable, and everything works as you’d want it to. The button is responsive, the USB port is completely flush with the bottom of the device and the mouthpiece pops on and off easily enough but there’s no danger of it coming off accidentally. No complaints at all here.